1. Field of Invention
The invention relates to a tightener for a binding strap and, in particular, to a device that tightens a binding strap.
2. Related Art
FIG. 13 shows a conventional tightening structure for a binding strap. It includes a base 8 having an axle hole 811 on each of its two sides for a rotating axle 82 to go through. One end of the axle 82 is connected with a driving element 83 that has several through holes 84. The body of the axle 82 has a long cutting groove 85 for a binding strap to go through. The rotating axle 82 is provided with a single-direction ratchet 87 on the outer side of the base. A stopping block 88 is disposed above the ratchet 87 and on the outer side of the base 8 to function with the ratchet 87.
The above-mentioned tightener has one acting bar (not shown) inserting into the through hole 84 of the driving element 83. By rotating the driving element 83, the axle 82 is driven to gradually tighten the binding strap 86. To release it, one has to depart the stopping block 88 away from the teeth of the ratchet 87. In this case, the axle can rotate freely and one can readily pull out the binding strap 86. However, it is not easy to move the stopping block 88 away when the ratchet 87 tightly snaps the binding strap. One has to exert a force on the acting bar toward the driving direction in order for the ratchet 87 to slightly relax for the user to relieve the stopping block 88. This shows its inconvenience and danger in uses.
To solve the above-mentioned problem with the conventional tightener, there is another design of the tightening structure for the binding strap in the prior art. As shown in FIGS. 14 and 15, it includes a base 9 having an axle hole 91 on each of the two sides. A rotating axle 92 goes through the two axle holes 91. The rotating axle 92 has a long groove 93 for the binding strap to go through. One end of the rotating axle 92 is connected with a driving element 94. The driving element 94 has several through holes 941, a swinging arm 942 and a cam part 943. The swinging arm 942 has an engaging block 944. The cam part 943 has a stopping block 945. The rotating axle 92 has a ratchet 95 on the outer side of the base 9. On the outer side of the base 9 and above the ratchet 95, there is a tooth 96 engaging with the ratchet 95.
When operating the above-mentioned tightener, the user inserts an acting bar (not shown) into one through hole 941 of the driving element 94. By moving the driving element 94 reciprocally in the vertical direction, the engaging block 944 rotates the rotating axle 92 of the ratchet in a single direction. The tooth 96 prevents the ratchet from rotating backwards. This gradually tightens the binding strap. To release the binding strap, the user has to depart the engaging block 944 from the ratchet 95. By rotating the driving element 94 now, the cam part 943 pushes the tooth 96 away from the ratchet 95. This relieves the binding strap.
Nonetheless, the second conventional tightener has more complicated structure and components. This renders higher component and assembly costs. The tighteners thus produced are more expensive and less attractive to consumers. It is an objective of the invention to solve these problems.